1. Field of the Invention
The present invention is generally directed toward conveyor systems and, more particularly, toward tow conveyor systems incorporating devices for preventing debris from interfering with the conveyor operation.
2. Description of Related Art
A tow conveyor system includes a chain having a number of chain links joined together end-to-end to form a continuous or endless chain that is received in a track. The links are typically joined so as to allow a degree of pivotal motion to accommodate bends in the track.
As shown in FIG. 8, a prior art conveyor chain 10 is received within a recessed track or channel 12, formed by a metal structural member 14 that is disposed under a factory floor 16. The conveyor chain 10 is configured to receive a kingpin 18 extending downwardly from a mobile carrier or cart (not shown) that is pulled by the chain 10 past one or more workstations.
Conveyor systems are often used in manufacturing facilities, where various components of a manufactured article are assembled at each work station. Such assembly may use various fasteners, including threaded members such as bolts. Often, bolts 20 and other such debris are dropped and end up on the floor. This debris can find its way into the recessed channel 12 housing the conveyor chain 10. In some circumstances, the debris becomes wedged between the chain 10 and the side of the channel 12, causing the chain 10 to have an uneven or jerking motion. Sometimes, the debris jams the chain 10, breaking one or more shear pins on the main gear box drive, and requiring the conveyor to be shut down until necessary repairs can be made.
In response to this problem, it has been proposed, as shown in FIG. 8, to provide a pair of horizontal plates 22 that are disposed over the top of the channel 12 and have side surfaces that face each other at a fixed distance, so as to define a slotted aperture 24 over the top of the channel 12. A series of semi-rigid brushes 26 project inwardly from beneath the side surfaces and extend toward each other. In this way, it was expected that the brushes 26 would prevent bolts 20 and other debris from entering the slotted aperture 24 and interfering with the chain 10, while still allowing the kingpin 18 to move through the slotted aperture 24.
However, it has been found that the brushes 26 are ineffective at preventing debris from entering the channel 12. It is believed that the brushes 26 deform over time as a result of repeated engagement with the kingpins 18, causing a gap to develop between the brushes 26 that allows debris to fall into the channel 12. Further, since the brushes 26 are disposed below the floor surface, it is believed that once debris is received by the brushes 26, it is difficult for the debris to escape except for passing through the brushes 26 into the channel 12. It is also believed that the brushes 26 lack strength to hold certain types of debris, and that the kingpin 18 may actually force the debris past the brushes 26. In any event, the brushes 26 require frequent maintenance and replacement in order to maintain their effectiveness, and conveyor downtime remains a problem despite this proposed remedy. Accordingly, there exists a need in the art for a structure that prevents debris from interfering with conveyor operation.